comnum.ais_decode

comnum.ais_decode(bits)

Decode the bits of an AIS message (ITU-R M.1371-5, Annex 8): the position reports (messages 1, 2, 3, 18), the base station report (4), the static and voyage data (5) and the class B static data (24); any other message gives its type and MMSI.

Parameters:

bits (array_like) – the message bits, most significant first (the payload of a sentence, ais_messages()).

Returns:

msg_type, mmsi, repeat and the fields of the message: a position (lon_deg, lat_deg, accurate, sog_knots, cog_deg, heading_deg, timestamp; None for a value “not available”) and nav_status, rot_raw, manoeuvre, raim (1, 2, 3); utc, epfd (4); imo, callsign, shipname, ship_type, dimensions, eta, draught_m, destination, dte (5); cs_unit (18); part and shipname or ship_type, vendor, model, serial, callsign, dimensions (24).

Return type:

dict

Raises:

ValueError – for fewer than 38 bits, a type outside 1 to 27 or a message shorter than its table.

Examples

>>> import comnum
>>> bits = comnum.ais_position_report(200000001, lat_deg=46.12, lon_deg=-9.88, sog_knots=8.0)
>>> m = comnum.ais_decode(bits)
>>> m["msg_type"], m["mmsi"], round(m["position"]["lat_deg"], 2)
(1, 200000001, 46.12)